A trend day can occur in either the same or the opposite direction to the prevailing trend on daily charts. The critical point is that the increased spread between the high and low of the daily range offers a trading opportunity from which large profits can be made in a short time.
Traders must understand the characteristics of a trend day, even if interested only in intraday scalping. A trader anticipating a trend day should change strategies, from trading off support/resistance and looking at overbought/oversold indicators to using a breakout methodology and being flexible enough to buy strength or sell weakness. A trader caught off guard will often experience his largest losses on a trend day as he tries to sell strength or buy weakness prematurely. Because there are few intraday retracements, small losses can easily get out of hand. The worst catastrophes come from trying to average losing trades on trend days.
Fortunately, it is possible to identify specific conditions that tend to precede a trend day. Because this can easily be done at night when the markets are closed, a trader can adjust his game plan for the next day and be prepared to place resting buy or sell stops at appropriate levels.
Classic Trend Day - A large opening gap created a vacuum on the buy side. The market opened at one extreme and closed on the other. Note how it made higher highs and higher lows all day. Also, volatility increased in the latter part of the day--another characteristic of trend days.